Engine starter drive



c. s. JANES ENGINE STARTER DRIVE April 20, 1943.

Filed May 20, 1940 2 Sheets-Sheet l R Y wm wm d i m w &, W

' m which the inertia of Patented Apr. 20, 1943 ENGINE! STARTER DRIVEClinton S. Janos, Elmira Heights, N. Y'., assignor to Bendix AviationCorporation, South Bend, Ind., a corporation of Delaware Application May20, 1940*, Serial No. 336,249

9 Claims.

The present invention relates to an engine starter drive and moreparticularly to gearing for connecting a starting motor to a member ofan engine to be started.

In connection with the provision of starting equipment for internalcombustion engines and more particularly automotive power plants, spacelimitations are becoming more and more restrictive, particularly asrespects the overall length of the drive gearing. The prevalent locationof the starting motor at the side of the engine, with the starter driveengaging a ring gear on the engine flywheel, brings the drive gear intoclose proximity with the floor boards of the vehicle, and frequentlynecessitates the formation of a clearance recess in the floor, or even alengthening of the wheel base of the car to accommodate the drive.

Moreover, in engine drives of the type in which a pinion isautomatically traversed into mesh with an engine gear by the initialacceleration of. a screw shaft, it is sometimes found that fouling ofthe screw threads and bearing surfaces with congealed lubricant orforeign matter, delays or even prevents the traversal of the pinion.Increasing the inertia of the pinion by attaching counterweights theretois not an entirely satisfactory solution of this difficulty since theinertia which resists rotation of the pinion also tends to resisttraversal thereof. Moreover, increasing the inertia of the pinion andits associatedparts tends to aggravate rebounding of the pinion towardthe engine gear when it is thrown out of mesh.

It is an object of the present invention to provide a novel starterdrive which is small and compact, particularly as regards overalllength, without sacrificing mechanical strength or durability.

It is another object to provide such a device in which the moving partsare enclosed and protected from the accumulation of foreign matter. Itis another object to provide such a, device incorporating provisions toinsure traversal of the pinion on rotation of the drive shaft.

It is another object to provide such av device the pinion as respectsrotation is increased without increasing its inertia as respectslongitudinal movement.

It is a further object to provide such a device in which means areincorporated to prevent rebounding of the pinion toward. the engine gearwhen it is thrown out ofmesh.

It. is another object. to provide such a device in which, the energy ofrebound of .the pinion is dissipated frictionally.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawings in which:

Fig. 1 is a sectional view partly in side elevation of a starter driveembodying a preferred form of the invention;

Fig. 2 is an end view thereof from the right in Fig. 1;v

Fig. 3 is a side elevation partly in section of the same structureshowing the parts in cranking position;

Fig. 4 is a section line 4-4 of Fi 1;

Fig. 5 is a sectional view partly in side elevation of a secondembodiment of the invention;

Fig. 6 is a view similar to Fig. 5, showing the parts in crankingposition;

Fig. '7 is an. end view from the right of the structure shown in Figs. 5and 6; and.

Fig. 8 is a section taken substantially on the line 8-8 of Fig. 5.

In Fig. 1 of the drawings there is illustrated a power shaft l which maybe the extended armature shaft of the starting motor, not shown. Adriving head member 2 is rigidly mounted on the end of the power shaft Iby any suitable means such as a cross pin 3 retained by a lock ring 4.Driving head 2 is provided with a radial flange 5 rigidly fixed thereonin any suitable way as by brazing or welding.

A pinion 6 is slidably journalled on the power shaft for longitudinalmovement into and out of engagement with a member such as a gear i of anengine to be started. A screw shaft 8 is fixed in any suitable manner asby welding or brazing on the end of the pinion 5, and a nut member 9normally in telescopic relation with the pinion 3 is provided with asmooth portion H normally bearing on the periphery of the screw shaft 8,and with internal threads 12 adapted to engage the threads of the screwshaft upon relative rotation thereof. A driven head in the form of aradial flange I3 is formed on the nut 9 or rigidly mounted thereon inany preferred manner, and a yielding driving member l4 here shown in theform of a coiled spring is provided for connecting the driving anddriven heads. As here illustrated, the connection is formedby means ofslots l5 and I6 formed in the driving. and driven heads respectively andadapted to receive outturned ends I! and I3 of the drive spring M.

A barrelmember l9 enclosing the. moving parts of the drive is providedwith an inturnedflange taken substantially on the 2| engaging andforming an abutment for the flange of the driving head 2. A thrust plate22 is mounted in the opposite end of the barrel l9, being retainedtherein a by means of a split lock ring 23. Thrust plate 22 is normallyengaged by the driven head l3 of the nut member 9 whereby the barrelserves to maintain the drive spring l4 under slight compression. Screwshaft 8 is provided with a shoulder 24 adapted to engage the thrustplate 22 when the pinion 6 is fully meshed with the engine gear 1 sothat said plate acts as an abutment to define the operative position ofthe pinion. As the shoulder 24 of the screw shaft is thrust against theplate 22 by the screw jack action of the screw shaft and nut during the.

cranking operation, torque is frictionally transmitted from the drivehead 5 through the barrel l9 and plate 22 to the screw shaft and pinion.The torque transmitted by the frictional clutch connection soconstituted is supplemental to the torque transmitted through the spring|4.

Means for insuring initial engagement of the threads of the screw shaftand nut is provided in the form of a spring 25 interposed between thedriving head 2 and the pinion. Means normally maintaining the pinion andscrew shaft in idle position is provided in the form of an anti-driftspring 26 surrounding the pinion and bearing against a flange 21 in theinterior of the thrust plate and the'shoulder 24 of the screw shaft.

In the operation of this embodiment of the invention starting with theparts in the positions illustrated in Fig. 1, rotation of the powershaft is transmitted through the drive head '2 and spring M to thedriven head I3 and nut 9. The pinion 6 and screw shaft 8, by reason oftheir inertia as respects rotation, are thereby moved to the left untilthe shoulder 24 engages the thrust plate 22, at which time the pinion 6is fully meshed with the engine gear. Further rotation of the nut 9causes it to move to the right, compressing the drive spring |4 untilthe end of the nut engages the drive head as illustrated in Fig. 3; Thespring I 4 is then wound up by the rotation of the power shaft I untilsufficient torque is built up to cause rotation of the pinion 6 to crankthe engine. When the engine starts, the acceleration of the engine gearI rotates the pinion 6 and screw shaft 8 faster than the nut 9 wherebythe parts return to their normal positions, the screw shaft running offthe ends of the threads of the nut and overrunning until its excessmomentum is dissipated.

If, during the meshing operation, tooth abutment should occur betweenthe pinion and engine gear, the tendency to jam is relieved bycompression of the drive spring |4 until suiiicient friction is built upin the threads of the screw shaft and nut to index the pinion intoproper registry with the tooth spaces of the engine gear, whereupon thedrive spring expands and snaps the pinion into mesh and crankingproceeds as above set forth.

In the embodiment of the invention illustrated in Figs. 5 to 8,inclusive, the power shaft 3| has a drive head 32 fixed thereon in anysuitable manner as by means of a pin 33. A pinion 34 is slidablyjournalled on the power shaft 3| for longitudinal movement into and outof engagement with a member such as a ring gear 35 of an engine to bestarted. A screw shaft 35 is rigidly mounted on the rear end of thepinion 34 as by brazing as indicated at 31, and a nut 38 is threaded onthe screw shaft and is provided with head. A torsion drive spring 4|surrounds the screw shaft 36 and nut 38 and is provided with outturnedends 42 and 43 arranged to enter radial slots 44 and 45 in the drivinghead 32 and driven head 39 respectively so as to anchor the ends of thespring to said heads.

A barrel 46 is arranged to surround and enclose the elements of thedrive and is provided at one end with a thrust ring 41 adapted to abutagainst the driving head 32. A thrust plate 48 is mounted in theopposite end of the barrel ad-- I jacent the normal position ofthedriven head 39.

As here shown, thrust plate 48 is frictionally connected for rotationwith the barrel by virtue of a look ring 49 and washer 5| which retainthe thrust plate in the barrel, and a spring washer 52 which bears atits rim against a shoulder 53 in the interior of the barrel and isdished as indicated so as to press the thrust plate 52 against thewasher 5|. Thrust plate 48 is preferably provided with internal teeth 54(Fig. 8) which engage slidably between the teeth of the pinion 34 so asto spline the thrust plate to the pinion. The barrel 46 is thus splinedto the pinion 34 through its frictional clutch connection with thethrust plate 48.

The forward end of the screw shaft 36 is arranged to engage the abutmentplate 48 when the pinion is fully engaged with the ring gear asillustrated in Fig. 6. An annular recess 55 is preferably provided inthe forward end of the screw shaft 36 in order to hous an anti-driftspring 56 which surrounds the pinion and bears at its ends against theabutment plate 48 and screw shaft 36 in order to normally maintain thepinion in idle position.

In the operation of this embodiment of the invention, starting with theparts in the positions illustrated in Fig. 5, actuation of the powershaft 3| by a starting motor, not illustrated, causes rotation of thedriving head 32 which is transmitted through spring 4| to the drivenhead 39 and nut 38. Pinion 34 and screw shaft 36 are initially preventedfrom rotation both by their own inertia and by the inertia of theabutment plate 48 and barrel 46 which are in effect splined to thepinion. The rotation of the nut 38 therefore threads the pinion andscrew shaft to the left, causing the pinion to engage the ring gear 35until the end of the screw shaft 36 engages the abutment plate 48 asillustrated in Fig. 6. During this engaging movement, it will be notedthat the abutment plate 48 and barrel 46 are not required to movelongitudinally so that their inertia while effective to prevent rotationof the pinion and a radial flange 39 at one end forming a driven 7.5

screw shaft so as to enforce traversal thereof, does not impede suchtraversal since at this time the abutment plate and barrel act in effectas a stationary detent splined to the pinion.

After engagement of the pinion with the ring gear, further rotation ofthe power shaft causes the nut 38 to move to the right, compressing thedrive spring 4| until the nut comes into contact with the driving head32 as illustrated in Fig. 6. At this time, the end thrust of the screwshaft 36 against the abutment plate 48 is transmitted through the barrelto the thrust ring 41 which bears against the drive head'32 so as totake the reaction from the compression of the drive spring 4|. After thedrive Spring 4| is thus compressed,

it is wound up by the torque applied by the power shaft to overrun thenut 38 whereby the parts are returned to their idle positions.Rebounding of the pinion into attempted mesh with the ring gear 35 iseffectively prevented by the frictional connection between the barrel 46and the anchor plate 48. When the parts are thrown back to idleposition, the barrel 46 continues to rotate until its momentum isdissipated by its frictional connection with the pinion, and during thisinterval, the pinion is firmly held in its idle position by reason ofthe torque thus frictionally applied thereto by the barrel.

Although but two embodiments of the invention have been shown anddescribed in detail, it will be understood that other embodiments arpossible and various changes may be made in the design and arrangementof the parts without departing from the spirit of the invention asdefined in the claims appended hereto.

What is claimed is:

1. In an engine starter drive, a power shaft, a

pinion slidably journalled thereon for movement into and out ofengagement with a member of an engine to be started, a screw shaft fixedat one end to the pinion, a nut having a driven head threaded on thescrew shaft, a driving head member fixed on the power shaft, a yieldingdriving member compressed between the driving and driven heads by thescrew jack action of the screw shaft and nut, and a barrel memberenclosing the drive having thrust means at one end bearing against thedriving head, and a thrust plate in the other end of the barrel againstwhich the nut is normally maintained by the expansion of the yieldingdriving connection, said screw shaft having a shoulder adapted to engagethe thrust plate 5 to limit the engaging movement of the pinion.

2. In a starter drive as set forth in claim 1, an anti-drift springlocated on the pinion and screw shaft between the thrust plate andshoulder urging the screw shaft and pinion toward idle position.

3. An engine starter drive including a power shaft, a pinion journalledthereon for longitudinal movement into and out of engagement with anengine gear, a screw shaft fixed at one end to i the pinion, a nutthreaded on the screw shaft and normally in telescopic relation with thepinion, a driving head fixed to the shaft, a driven head on the nut, anabutment defining the idle position of the nut, a yielding drivingconnection between i the driving and driven heads surrounding the pinionand nut, and a barrel enclosing the drive having a torque-transmittingconnection with the pinion supplemental to said yielding drivingconnection during the cranking operation.

4. In an engine starter drive, a power shaft, a driving head having aradial flange fixed thereon, a pinion journalled on the power shaft, ascrew shaft fixed to the pinion, a nut on the screw shaft having adriven head, a yielding driving connection between the driving anddriven heads, and a barrel enclosing the drive having a slidable torquetransmitting connection with the pinion supplemental to said yieldingdriving connection.

5. In an engine starter drive, a power shaft, a drive head having aradial flange fixed thereon, a pinion journalled on the power shaft, ascrew shaft fixed to the pinion, a nut on the screw shaft having adriven head, a yielding driving connection between the driving anddriven heads, and a barrel having a yielding torque-transmittingconnection to the pinion supplemental to said yielding drivingconnection, said barrel having means limiting separation of the drivingand driven heads.

6. An engine starter drive as set forth in claim 4 in which the yieldingdriving connection between the barrel and pinion includes a frictionclutch.

'7. An engine starter drive as set forth in claim 4 in which theyielding driving connection between the barrel and pinion includes afriction clutch, and torque-responsive means for tightening the clutch.

8. In an engine starter drive, a power shaft, a drive head having aradial flange fixed thereon, a pinion slidably journalled on the powershaft, a screw shaft fixed to the pinion, a nut on the screw shafthaving a driven head, a yielding driving connection between the drivingand driven heads, and a barrel enclosing the drive having thrust meansin one end engaging the driving head and a thrust plate in the other endsplined to the pinion.

9. In an engine starter drive, a power shaft, a drive head having aradial flange fixed thereon, a pinion slidably journalled on the powershaft, a screw shaft fixed to the pinion, a nut on the screw shafthaving a driven head, a yielding driving connection between the drivingand. driven heads, a barrel enclosing the drive having thrust means inone end engaging the driving head and a thrust plate in the other endsplined to the pinion, and a friction clutch connection between theclutch plate and the barrel, the screw shaft having a shoulder engagingthe thrust plate to compress the friction clutch responsive to crankingtorque.

CLINTON S. J ANES.

